A condensing boiler is a home heating system that is designed to recoup energy that conventional furnaces and boilers lose. Most houses have small pipes that discharge excess heat out through the roof - they often look like small chimneys. Condensing boilers capture this excess energy and put it to use. The reason for the name is that a condensing boiler literally condenses the water vapor produced by the consumption of gas or oil in the boiler condenses back into water. This condensation, in turn, allows the latent heat involved in the vaporization of the water to be used usefully in heating your home.

As of 2007, condensing boilers are now often replacing "conventional" systems in Europe. The Netherlands led the way, but now other nations, particularly those with aggressive "green" goals or high fuel costs, have also joined the rush toward the use of condensing boilers. In the United States there has been a more recent serious look at these furnaces on a large scale, particularly as gas and oil prices have skyrocketed.

So, what would the conversion to a condensing boiler system mean to your home? First the scientific explanation: A condensing boiler achieves up to 98% thermal energy efficiency. The system you have now, assuming it’s a conventional system, probably only has about 70%-80% efficiency. What does that mean for your bill? You could see a difference of between 30-40% on your home heating bill by installing these systems. And all the while you will be reducing you and your family's "carbon footprint", helping reduce problems such as reliance on foreign oil and global warming.

In order to get the maximum benefit from a condensing boiler, a precise control system should be installed. A basic room thermostat will not be enough to ensure you are saving money and reducing emissions. A better method, for example, is to use an outdoor weather sensor to enable the boiler to heat the home only to the temperature needed. This and other controls can also signal the boiler when to run in the "condensing" mode.

Right now, condensing boilers are up to 50% more expensive to buy and install than conventional types of furnaces and boilers. However, state and federal grants and rebates might help offset that additional cost. Even so, the extra cost of installing a condensing boiler could be recovered in about 2-5 years at US 2007 oil and gas prices. Of course, this depends on the climate where you live, but it’s a given that after a relatively short period of time, your condensing boiler will be saving you money every day you heat your home!